One LLC for each property, or just batch them into groups of properties by area/town/street.

Legal probably wont run you 4x what it normally does as I'm assuming its all batched into the same purchase from same seller will probably be more extensive than 1 deal....While its hard to know exactly what your costs would be, on your scale, i would probably venture closer to 50k than 5k but wouldn't think quite that much. 

I know there is a mixed opinion in BP about what marketing pieces work better,  letters or post cards.I'm about to send my second batch of letters/postcards.

It's in a smaller batch to find the one that will work and then I plan to ramp it up.

I'm not super responsive when clients start asking me or their agent more than one batch of questions about the property... by the time client is on their 3rd or 5th batch of questions, whoops, someone else already got the property.

At a minimum consider driving for dollars instead to build your list and factor in a lower response rate for your competitive market.Since you haven't started yet, here's protip #1 for DM:Always send your first batch FIRST-CLASS, postcard.

I only want to know because I will be sending out my first batch of mailers very soon and I want to be as professional in appearance as possible.Any little tid-bits "that nobody tells you till its too late" (if any) would be great.

Little before and after pics, with numbers; we are working our way through 50 some units, this is a batch of 24 of them.

But I think it's just a fresh batch of new BP users that try to buy some list and try their luck.  

@Michael K GallagherOr get a new number and send a batch email to all contacts with your new contact info and text individuals with a template.